Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region |
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| Authors: | Dan M. Arriesgado Hiroyuki Kurokochi Yuichi Nakajima Yu Matsuki Wilfredo H. Uy Miguel D. Fortes Wilfredo L. Campos Kazuo Nadaoka Chunlan Lian |
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| Affiliation: | 1. Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo, Japan;2. Asian Natural Environmental Science Center, The University of Tokyo, Nishitokyo, Tokyo, Japan;3. Institute of Fisheries Research and Development, Mindanao State University at Naawan, Naawan, Misamis Oriental, Philippines;4. Marine Science Institute, University of the Philippines, Diliman, Quezon City, Philippines;5. Division of Biological Sciences, College of Arts and Sciences, University of the Philippines in the Visayas, Miag‐ao, Iloilo, Philippines |
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| Abstract: | Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (FST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change. |
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| Keywords: | Clonality
Cymodocea rotundata
genetic diversity Kuroshio Current seagrass hotspot simple sequence repeat markers tropical pioneer species |
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